Uveitis is the leading cause of legal blindness in the United States. Elucidation of initial events in the development of uveitis could provide new therapeutic approaches to the management of this blinding disease. These studies are based on the hypothesis that bone marrow-derived cells initiate uveitis by presenting retinal antigens to CD4+T-cells and such bone marrow-derived APCs may be present in the retina and/or choroid. This hypothesis will be tested using bone marrow chimeras with adoptive transfer of S-antigen specific T-cell lines. Specifically, the application will: (1) determine the role of bone marrow-derived cells in experimental autoimmune uveoretinitis (EAU) by transfer of specific T-cells to chimeras, (2) identify and localize the bone marrow-derived cells in retina and choroid and (3) determine the cytokine profile of these cells during the development of uveitis. This will be accomplished by a team of investigators with expertise in immunopathology, immunohistochemistry, in situ molecular techniques and molecular biology.